On spinodal decomposition in alnico---a transmission electron microscopy and atom probe tomography study

Alnico is a prime example of a finely tuned nanostructure whose magnetic properties are intimately connected to magnetic annealing (MA) during spinodal transformation and subsequent lower temperature annealing (draw) cycles. Using a combination of transmission electron microscopy and atom probe tomography, we show how these critical processing steps affect the local composition and nanostructure evolution with impact on magnetic properties. The nearly 2-fold increase of intrinsic coercivity ($H_\text{ci}$) during the draw cycle is not adequately explained by chemical refinement of the spinodal phases. Instead, increased Fe-Co phase ($\alpha_1$) isolation, development of Cu-rich spheres/rods/blades and additional $\alpha_1$ rod precipitation that occurs during the MA and draw, likely play a key role in $H_\text{ci}$ enhancement. Chemical ordering of the Al-Ni-phase ($\alpha_2$) and formation of Ni-rich ($\alpha_3$) may also contribute. Unraveling of the subtle effect of these nano-scaled features is crucial to understanding on how to improve shape anisotropy in alnico magnets

Simulation of alnico coercivity

Micromagnetic simulations of alnico show substantial deviations from Stoner-Wohlfarth behavior due to the unique size and spatial distribution of the rod-like Fe-Co phase formed during spinodal decomposition in an external magnetic field. The maximum coercivity is limited by single-rod effects, especially deviations from ellipsoidal shape, and by interactions between the rods. Both the exchange interaction between connected rods and magnetostatic interaction between rods are considered, and the results of our calculations show good agreement with recent experiments. Unlike systems dominated by magnetocrystalline anisotropy, coercivity in alnico is highly dependent on size, shape, and geometric distribution of the Fe-Co phase, all factors that can be tuned with appropriate chemistry and thermal-magnetic annealing

A Clustering Algorithm Based Geographic Location Information for Wireless Sensor Networks

Abstract: One of the main objectives of wireless sensor network design is to improve the energy efficiency. How to efficiently utilize sensor nodes to prolong the lifespan of a wireless network has long been a research topic. This paper presents a location based LEACH clustering algorithm, which is an extension to the LEACH routing algorithm. Armed with distributed and local network based routing decision-making mechanism, this algorithm fully utilizes the location information of network nodes in routing to reduce the routing cost. Simulation results indicate that this algorithm can balance nodes' energy consumption and prolong the network's life span. It also has good stability and extensibility

Selection of Ovine Oocytes by Brilliant Cresyl Blue Staining

Sheep oocytes derived from the ovaries collected from the slaughterhouse are often used for research on in vitro embryo production, animal cloning, transgenesis, embryonic stem cells, and other embryo biotechnology aspects. Improving the in vitro culture efficiency of oocytes can provide more materials for similar studies. Generally, determination of oocyte quality is mostly based on the layers of cumulus cells and cytoplasm or cytoplasm uniformity and colors. This requires considerable experience to better identify oocyte quality because of the intense subjectivity involved (Gordon (2003), Madison et al. (1992) and De Loos et al. (1992)). BCB staining is a function of glucose-6-phosphate dehydrogenase (G6PD) activity, an enzyme synthesized in developing oocytes, which decreases in activity with maturation. Therefore, unstained oocytes (BCB−) are high in G6PD activity, while the less mature oocytes stains are deep blue (BCB+) due to insuffcient G6PD activity to decolorize the BCB dye

Nontrivial Solutions for Periodic Schrödinger Equations with Sign-Changing Nonlinearities

We prove a new infinite-dimensional linking theorem. Using this theorem, we obtain nontrivial solutions for strongly indefinite periodic Schrödinger equations with sign-changing nonlinearities

Nontrivial Solutions for Periodic Schrödinger Equations with Sign-Changing Nonlinearities

We prove a new infinite-dimensional linking theorem. Using this theorem, we obtain nontrivial solutions for strongly indefinite periodic Schrödinger equations with sign-changing nonlinearities

Random Integer Lattice Generation via HNF

Lattices used in cryptography are integer lattices. Defining and generating a random integer lattice are interesting topics. A generation algorithm for random integer lattice can be used to serve as a random input of all the lattice algorithms. In this paper, we recall the definition of random integer lattice given by G.Hu et al. and present an improved generation algorithm for it via Hermite Normal Form. It can be proved that with probability >= 0.99, this algorithm outputs an n-dim random integer lattice within O(n^2) operations